I have myself a brand new 2018 XLT Supercrew, with the 18 inch chrome wheels. And I'm not really crazy about chrome wheels.

Looking on the local Craigslist, I find new take offs, 20 inch Ford wheels and tires, for around $1200. If I do this, will I need to have my speedometer re-calibrated, or does the diameter wind up about the same?

Yes, I could do some research, look up exactly what size tires I have, and excatly what size tires come in the factory 20 inch package, and use the calculator at Tire Rack, but hey, I'm lazy, and I'll bet others have already done the homework.

 

How do you expect us to tell you without knowing both tire sizes?

You know how to do it, don't be so lazy and expect us to do it all for you!

 

glc is right... don't be lazy.

 

275/55/20 stock tires and wheels. 18's I have no idea.

 

The 18’s are very likely 275/65/18. Both tires are very compatible in size/diameter and the swap of OEM wheels and tires will have no effect in the truck.

 

I figure that since Ford put 20" wheels on the outside and chose to give me an 18" wheel spare, they must be pretty close to same overall dia... Which they are if you do the math..



Mitch

 

My tires are 265/60 R18. If the 20 inch Ford wheels and tires are indeed 275/55 R20, then the circumference goes from 30.5 inches to 31.9 inches, a difference of +4.6%.

So 70 mph indicated would be 73.22 mph. Would I want to pay for a recalibration based on that small of a difference? Hmmm….

 

Yes, because it would also affect the way it runs, transmission shift points, etc.

 

Most Fords OEM tires are undersized compared to odometer readings. You can quickly find this out by checking your mileage using road mileage markers or good gps. My last 3 Fords the odometer was off almost 1/10 mile. By putting on slightly larger tire diameter the odometer reading is closer to corrected.
In any event going up an inch doesn’t warrant recalibration of the speedo.